Press control



7 Sept. 24,1;l946. a L. s. HUBBERT 2,408,312-

PRESS CONTROL Filed Nov. 5, 1943 2 Sheets-Sheet 1 llll INVENTOR LESLIE 6. HUBBERT ATTORNEYS Patented Sept. 24, 1946 mass ooNrnoL Leslie S. Hubbert, Mount (iileadyOhio, assignor to The Hydraulic Development corporation, Inc., Wilmington; De1., a corporation of Delaware Application'November 5, 194 3 Serial d This invention relates generally to hydraulic presseslandhas for its primary object the pro vision ofja manual and automatic control linkage" whereby it is possible'accurately to control the rate of travel and position of the press platen during its reciprocation to and from thework.

In many classes of work, such asbendingand straightening and some forging operations, it -isdesirable .that the press platenbe underlthe control of the operator at all times 'both asto position and ratepf travel., Particularly in the straightening of shafts and similar objects" precise positioning of the press platen relative 'to the work is essential; 1111 an operation of this type, it is also desirableithat the operator be able to retract the platen from the work a short distance inorder to gage the work piece or insert a new one as the'caseniay be. j

By means of the control system of this invention, it is possible to accomplish these results readily. V The foregoing will be more apparent upon reference to the following detailed description taken in connection with the attached drawings. in the drawings:

.Figure 1 is a rather diagrammaticiview of a v hydraulic press having a control'system embodying this invention.

Figure '2 is a view of one form of hydraulic system. adapted to be controlled by. this control system. I 1

Figure 3 isa wiring diagram of the electrical system associated with this'control. i

Referring to the drawings more in detail, and in particular to Figure 1,,the hydraulic "press shown therein comprises a frame member generally indicated at I0 "having bed portion .at

and carryin'ga press cylinder at l2;

Reciproca'bly mounted within the ,cylinder lz is a press ram or platen l3 adapted to move into and out of engagement with the Work as deter- :5

mined by the operator.

Mounted within the press frame I 0 arehydrau llc pumps I4 and' l5, the former being: a variable delivery pump and theflatter-being a constant delivery pump. These um s are connected id? R the c nd i t its .ee d i 'tf ed on to Figure-2, the aforementioned wh ms- 594 2? the Qtherside by the conduit l9 tov the conduit [1. fThpuin'p' liis adapted to draw fluid from thetank 2u through the conduit 21' and to expel it, a t increased pressure; into the conduit 22 which-joins through the check valve 23 with the 1 conduit l'6, andthrough the check valveTM with v the 'conduitifl. The conduit 22further comprises a relief lvalve 25 which is adapted, upon the accomplishment" 'of a *'predetermined pressure ,within'th conduit 22, to establish a fluid conneci tion from' -the conduit 22 through the conduit 26 back to the tank '20. Valv25 is preferably a low pressure relief valve and serves to discharge thefexcessfdischarge of the pump l5 when. it is unot de s iredj to utilize the full flow from the p mp; l 5 in the operation of the' press.

The conduit 16- 'nclude'sg between the cylinder "and tha'jllnction Ofconduits'flfi and IS, a valve'fz llT Thi's valve, which is-"an unloading or pilot bperat'ed relief valve, is for the" purpose .of discharging the fluid above the ram l3 to the tankduringtheretraction stroke. This'is necessarybecause the amount of' 'fluid'discharged from bove'the ram during the retraction stroke is i cavity" beneath the 'ra'm during the r retraction stroke]; The valve 21 connects-through"the condu'it 28 ans the low'pressurefrelief valve 29 with the tank 201 A' pilot'lin'e '30, the function of which isto operate" the valve 21, is connectedto the cOnduiE 'I-T-atflone end and into the pilot 'cylinder'of thev'alve fl at its opposite end.

Theilowjpressure relief valve 29 in the conduit.

285s for thepurpose 'of maintaining suflicient pressure Within' the conduit 28 to maintain the hydraulic system completely filled at all times. Referring again to Figure l, more particular reference will be made to the previously mentioned control systemftThis systemcomprises a screw 3| .which threads through an arm! 32 carried by the. ram 1 3. The screw 3! is journalled in the press frame Ill a 1 t 33*and passes through the gear box 34 of the "motor 35 'within'which-itis suitably splined or "slidably .keyed to the low' speed output 'gear of the gear b0X.'.. Th'e;lower end .of the screw 3| is splined as at 36 and carries a similarly splined bevelgear 31. The screwi3l also has pinned thereto alpaireof collars 38 which are adapted, as indicated in Figure '1, to engagethe end of a bell crank lever- 39'by means of which the valve delivery pump. l l'l'is' "shifted; .The. lever 39 is pivoted atlll on :the'jpress frame or any other similarlyistationa'ry member. -{rherg'earislgisdnzmesh Twiththe bevel gear 4!,

excess ofthe amount introduced into -the The shaft 45 extends left wardly through the wall of the bed Portion II 10.

of the frame In and has aiiixed to the end thereof and outside of the press bed thehand wheel 46. A pinned collar or other suitable means such as indicated at 41 retains the shaft 45in its prop.- 4

er position in the press bed.

The previously mentioned clutch members 43 and 44 comprise a magnetically operated clutch,

actuation of which is effected through the lever? 48, the solenoid 49 and the spring 59. The lever 48 is pivoted at 5| and is adapted, when the solenoid 49 is energized torotate clockwise thereupon and bring the clutch members 44 and 43 into driving engagement. Upon V deenergization of the solenoid 49 the spring 59 is effective to rotate the lever 48- counter-clockwise about-the pilot 5| and thereby to move the clutch member 44 away from the clutch member 43 thus destroying the driving connection therebetween. 1

The motor 35 is adapted to drive the. screw 3| through the gear box whereby to cause reciprocation of the press platen in 'a manner hereinafter described.

1 Referring now to Figure 3, there is illustrated the electric circuit employed to energize the motor 35 and the clutch solenoid 49. The circuit shown in Figure 3 comprises the electric mains 52 and 53 connected between ;which are the branches including the push buttons, contactors, solenoids and motor which comprise the electric circuit. 1

"Ihe first branch-line contains a push button 54 and a contactor solenoid A. A second line includes clutch solenoid 49 and the normally closed contactor blades AI and BI. The third branch line includes a motor '35 and apairoi normally open contactor blades A2. In parallel with A2-and 'alsoconnectedto the motor is a branch containing the normally open contactor blades B2. 7 ta'ctor solenoid B and the push button55.

The motor 35 is of the well known electrically reversible type and is adapted,- whenenergized by the means of the mains 52 and 53 through the blades A2 to rotate in one direction, and when energized through the bladesBZ to rotate in the opposite direction. i

Operation Assuming that the press ram is in'the position shown in Figure '1, andthat a work piece, as indicated by the dot-dash lines, is resting on the press bed, a work stroke will 'beinstituted by the operator bypressing thepush button 54. Closing of the push button 54 will energize the contactor solenoid A. Energization of the contactor solenoid A causes the normally closed blades Al to open and the normally open blades A2 to close. The opening of the blades AI de- A last branch line includes thecom energizesthe previously energized clutch, solenoid 49 and the'closing of the blades A2 energizes the motor 35 to rotate in one'dire'ction.

' The deenergization of the clutch solenoid 49 permits the spring 59 to open the clutch thereby disconnecting the driving connection'between the hand wheel 46 and the screw 3|. The rotarelatively to the arm 32.

4 tion of the motor 35 is effective to rotate the screw 3! through the gear box 34. Rotation of the screw 3| causes it to thread upwardly through the arm 32 and, by means of the collars 38 causes the bell crank 39 to shift the pump I4. The shifting'of the pump I4 causes fluid to be delivered into the conduit. I8 and thence through the conduit I6 into the chamber within the cylinder I2 and above the press ram I3. Fluid is also withdrawn from beneath the ram I3 through the conduit I1 and conduit I9. The press ram I3 moves downwardly due to this fluid transfer and carries with it the arm 32. Downward movement of the arm 32 tends to move the screw 3| downwardly to offset the previously mentioned upward movement of the screw 3| It will be apparent that the'rate of movement downwardly of the press ram I3 and attached arm 32 will be equal to the rate at which the screw 3| threads upward through the arm;32.' For this reason, the pitch of the screw 3| and the rate at which it is driven aredependent upon the rate at which the pumps I4 and I5'can supply fluid to cylinder I2.. The maximum rate atwhich the screw 3| threads upwardly through the arm 32 must be equal to the maximum rate at which the'ram I3 descends due to the aforementioned transfer of fluid to and from thecylinder I2 by the pumps I4 and I5. I s

Thev button 54 is held closed by the operator until the ram I3 approaches the work at which time the button 54 is permitted to open and the press ram halts. During this portion of the forward stroke, which is conducted at relatively high speed, 'the action of .the hydraulic circuit illustrated in Figure 2is as follows: The pump I4 is shifted, by means of the bell crank39jto fdeliver fluid into the conduit, I8 and thence, by means of the conduit I6, 'into the chamber above the press ram I3. The pump I4 also draws fluid through the conduit I9 and H from beneath therp'ress ram I3. The, weight of the ram I3 and the associated partsis sufficient to cause-the moving parts of the press to descend as rapidly as fluid is withdrawn from the cylinder I2 through the conduits I7 and I9. During this part of theforward stroke, the pump I5 delivers I. fluid through the check valve 23 into the conduit I6 and thereby makes up the difference between the amount of fluid withdrawn from beneath the ram, by the pump I4and the amount of fluid required to fill the cavity above theramIBfi .Also, withdrawal of fluid from the cylinder I2 through the conduit I'| will cause thepressure therein tobereduced to such as value that the valve 21, piloted by this pressure, will close. The closing of the valve. 21 seals off the fluid connection between the conduits- I 6 and '28 and thereby directs the dischargeof .pumps' I4 and I5 directly into the cylinder I2 above the ram.

As previously mentioned, when the press ram approaches the work the push button 54 is permitted to open thereby deenergizing the contactor solenoid A and opening the contactor blades A2.;to stop the motor 35.- Deenergization of the contactor solenoid A also permits the blades AI toclose thereby energizing theclutch solenoid 49. The operator may now control the movement of the press ram I3 by rotation of the hand wheel 46 as follows: Rotation of the hand Wheel 46 is communi oated, by means of the shaft 45, the now'engaged clutch members 44 and 43 and the shaft 42 into the bevel g'ear -4I. :Rotationi -ofuthejbevelo.gear 4I' causes rotati'on of the mating b'eveligear 31 which, through its 'splin'ed connection therewith,- rotates the screw 3|. In the'm'anneridescribed above, in connection'with automatic rotati'onuof the-screw, manual rotation of the screwi3l :will cause a corresponding reciprocation of theiiranrl I3. Theram I3 is thereby reciprocated byja manipulation ofithe hand wheel 46 ate io'ccupy any position desired by the 'operatoix 1 For "example, in the straightening:- of Ira Jshaft, it might be desireii t'o' move the platen.l3ilinto engagement with the work, "to further force'the platen under pressure into the work, andith'en to retract the platen slightly away from the work in order to-gage onother'wise measure the effect produced. Having caused the platen to approach the work under high speed, this is readilyaccomplished by means of the manual control at 46.

Retraction of the ram from the work to the position indicated in Figure 1, or any intermediate position, may be accomplished at relatively high speed by the closing of the push button 55. The closing of the push button 55 energizes the contactor solenoid B and thereby causes the normally open blades B2 to close and the normally closed blades Bl to open. The opening of the blades BI deenergizes the clutch solenoid 49 and permits the spring 50 to open the clutch as previously described. The closing of the blades B2 energizes the motor 35 to rotate in a direction opposite to that caused by the closing of the blades A2. The rotation of the motor 35 drives the screw 3| in a direction to thread downwardly through the arm 32. Movement of the screw 3| downwardly through the arm 32 causes the collars'38 to move the bell crank 39 to shift the pump I4 on stroke. The pump I4 now draws fluid in through conduit I8 and discharges fluid through conduit I9. The fluid discharge into the conduit I9 is conducted by means of the conduit I'I int cylinder I2 and mneath th press ram I3.

The passage of fluid through the conduits I9 and I1 into the cylinder I2 causes an increase in pressure in the conduit I! which is communicated through the pilot line 39 to the pilot cylinder of the unloading valve 21. The valve 21 is thus caused to establish a fluid connection between the conduits I6 and 28, and the fluid expelled from above the press ram I3, in excess of the amount required to fill the cavity beneath the press ram I3, is passed through the conduit 28 and the low pressure relief valve 29 to the tank 20. During this retraction stroke the pump I5 is either discharging through the relief valve 25 to the tank or through the check valve 23, valve 21, conduit 28 and relief valve 29 to the tank.

It will be apparent that the retraction area of the press ram I3 is of sufficient size that the full delivery of the pump I4 is suflicient to cause upward movement of the press ram to be equal to the maximum rate of downward movement of the screw 3l as the screw threads downwardly through the arm 32.

It will be noted that the clutch solenoid 49 is adapted to be continuously energized so long as the contactor blades AI and BI are closed. The energization of either of the contactor solenoids A or B is eifective to render inoperative the hand wheel 46. This is a safety feature insuring that there is never a driving connection between the screw 3| and the hand wheel 46 when the motor is energized to drive the screw 3| at high speed. It is possible to move the screw 3| by means-of the hand wheel 4:6 when and onlyv when,"'thegmdtor 335 is *deenergized. I Itwill be obvious that, due to th'e naturezof thepump I4, .the efiectof'the screw'3l is to. give a micrometeradjustment of the .rplatentposition. That is, the rate of reciprocation :of 113116 platen is dependent upon theamount 'by'whichztherpump I4'is shifted'on to stroke, andthatithe'ia'mount that the pump I'4t-is shifted'isfin turn dependent upon thespeed' of rotation of a'screw3l. It is furtheriapparent that the floworegulating means. need not necessarily consist .of a ;va-ri-' abledelivery pump but could aswellzconsist..-o-f a i four way valve connectedv with :the :screw' 31 either directly ori throiigh linkage. similar to the lever'3 9. It will be understood that I do not desire my invention to be limited to the particular structure shown in the drawings but desire to comprehend such modifications as may come within the spirit of the invention and the scope of the appended claims.

Having thus fully described my invention, what I claim as new and. desire to secure by Letters Patent is:

1. In a hydraulic press, a press platen, fluid motor means for reciprocating said platen, a source of pressure fluid, means forming a hydraulic circuit connecting said source with said motor and including control means for varying the rate of fluid flow, a rod threadedly engaging said platen for movement therewith and including means operatively connected with said control means, a reversible electric motorslidably v erable to energize said motor to operate in either direction, electrically actuated clutch means between said rod and said manual means operable when energized to disengage said manual means from said rod, and contactor means connected to be energized by said switch means and having contactor blades in circuit with said motor and said clutch means for positively deenergizing said clutch means simultaneously with the energization of said motor.

2. In a hydraulic press, a platen, a fluid motor for reciprocating said platen, a variable delivery pump connected to supply said motor, flow control means operable to control the rate and direction of the fluid supply from said pump to said motor, a threaded rod threadedly engaging said platen in a direction substantially parallel to the path thereof, an electric motor slidably keyed to the upper end of said rod for selectively rotating the same in either direction, manual means slidably keyed to the lower end of said rod and extending to the front of the press to the operators position for manual actuation of said rod in either direction, means on said rod between the ends thereof for engagement with said flow control member whereby movement of said rod in the axial direction is operable to adjust the rate of flow from said source, normally open switch means adapted for selectively energizing said motor to run in opposite directions, normally open clutch means between said manual means and said rod, and a solenoid adapted, when energized, to move the clutch to closed position, said solenoid beingconnected to be energized when said motor is de-energized and to be tie-energized when said motor is energized whereby said'manual means is always disconnected when'said motor is operating.

'3. In a hydraulic press, a press frame, a plunger reciprocably mounted in said frame, a reversible variable delivery pump for supplying fluid to said plunger control means movable to vary the rate and direction of delivery of said source for controlling the movement of said plunger, an arm carried by said plunger including a threaded bore, a threaded rod slidably mounted in said frameand engaging said bore, linkage interconnecting said rod andsaid control means for moving the latter in unison with the former, a reversible electric motor mounted in said frame adjacent .the upper end of said rod,

slidable key means interconnecting said motor and said rod, a bevel gear slidably keyed to the lower end of said rod, a second bevel gear in mesh with said first mentioned gear, a shaft extending from said second gear through said press frame to the operators position, manual means for turning said shaft, clutch means for connecting the manual means to the shaft and normally urged to disengaged position and having electrical means adapted when energized to move the clutch to engaged position, and circuit means interconnecting said electrical means with said motor and so arranged that when either is energized the other is de-energized.

LESLIE S. HU'BBERT. 

